The invention concerns a lockable ejection device for a moveable furniture part, comprising a control pin moveable in a cardioid-shaped sliding guide track. The sliding guide track has a closing portion in which the control pin moves upon closure of the moveable furniture part. A locking portion has a latching depression in which the control pin is held in the locking position, and an opening portion in which the control pin is moveable upon opening of the moveable furniture part. Arranged in the locking portion is an overload mechanism by which the locking position is releasable even upon movement of the moveable furniture part in the opening direction, and the overload mechanism has a blocking element which is subjected to a force and which temporarily blocks an overload path for the control pin.
Lockable ejection devices (also referred to as touch-latch mechanisms) are used in particular in relation to drawers and serve to provide that, when pressure is applied to the closed drawer, the drawer is unlocked and automatic ejection or opening of the drawer takes place. In the first designs of such lockable ejection devices, ejection could be effected only by pressing against the drawer (overpressing in the closing direction). If, however, when the drawer was closed it was not pressed but rather was pulled in the opening direction, individual components could be overloaded or even destroyed.
To avoid that problem, overload mechanisms were fitted in such lockable ejection devices. An example of such an overload mechanism is to be found in DE 20 2009 005 256 U1. In that case, the region in which the control pin is disposed in the locking position is rotated for example upon movement of the drawer in the opening direction, or an overload path is opened in the region of the “heart” of the cardioid-like sliding guide track. A variant also provides that the sliding guide track itself is formed from two parts and they are displaced relative to each other in an overload situation. In all embodiments according to the above-indicated specification, there must be a change in the normal, cardioid-shaped path for the control pin. As a result, regions of the actual sliding guide track are always blocked. Particularly when, after such an overload, the moving part no longer moves back into the normal position in good time, the normal cardioid-like path can no longer have the control pin passing entirely therethrough. That can result in defective triggering processes. It is, however, also possible for the closed position or the locking position to be no longer correctly attained.
In a similar fashion JP 2007-009507, in particular in FIG. 7 thereof, shows an overload mechanism in which a part of the “heart” of the cardioid-like sliding guide track can be pivoted in an overload situation and thereby opens a path for the control pin in the opening direction. This arrangement also suffers from the disadvantage that the normal path of the control pin is displaced by that pivotal movement. If that path is not cleared again in good time, the problems already referred to above can arise.
WO 2007/050737 A2 discloses a cardioid-shaped locking portion having a latching depression in which a control pin latchingly engages. A relatively narrow overload passage is already provided in the cardioid configuration, in the region of that latching depression. As the cardioid shape-forming parts comprise a flexible material, the control pin can be forced through those flexible parts, when an overload occurs. A disadvantage in that respect is that the flexible materials can wear away due to the control pin being forced therethrough, in multiple overload movements, whereby an unwanted increase in width of the passage can occur. That can result in an unwanted locking effect even with a normal load being involved or with a slight overload.